Here is the full explanation for scanning of old Keypads and Door stations
Old firmware for keypads and door stations which do not support the scanning command cannot be discovered by Comfort scanning of they are not polled
for example if the number of keypads is 1 and door stations is 0 in Comfort, and you connect keypad # 2 and Door station 1 and do a scan, the scan will not find the new keypad #2 and Door station #1
You need to add the keypad and door station manually by right click eg on Door station and select Add Door station

The door station will appear in gray meaning it status is not known as it has not been scanned yet
Do the same for the old keypad
Then do right click and select Write Modules and settings to Comfort
This will write the number of keypads and door station to Comfort. After this Comfort is reset automatically and the new keypad and door station will work
If you scan for modules again, the new door station will appear in black and status will be \"Polled\". The firmware version will be Unknown as the old door station does not support the scan commaand
However if you open an existing file in you have 2 keypads and 1 door stations, but the Comfort system does not have 2 keypad and 1 door station in memory and then do a scan, the keypad 2 and door station 1 will appear as \"Not Found\" in red
When you write to Comfort, Comfigurator willl not add the missing or Not found keypad and door station, so the 2nd KP and 1st DP will not work.
Remember we are talking about old keypads and door stations. New ones will not have this problem
I suspect this is what happened in your (juwi_uk) case
In summary you can handle the old firmware KP and DP if not added to Comfort by doing a manual add KP and DP and Write Modules to Comfort immediately, BEFORE doing a scan which would result in NOT FOUND status